1. Field of the Invention
The present invention relates generally to biopsy needles. In particular the present invention relates to needles used for obtaining a sample of tissue from a body for medical evaluation outside the body.
2. Discussion of Background
A biopsy involves removal of a sample of tissue from a body, without significantly affecting the body, for cytological and histological studies. Typically, tissue removal is done with a biopsy needle, a hollow needle with a tissue cutting and securing mechanism. A number of types of such needles are known and readily available.
For example, see U.S. Pat. No. 1,583,934 issued to Muir, U.S. Pat. No. 2,198,319 issued to Silverman, and U.S. Pat. No. 2,767,703 issued to Nieburgs all describe biopsy needles that require some rotation to remove tissue samples.
However, it is an important consideration in biopsy needle design that the amount of tissue removable be sufficient for the types of analysis to be done. Although major improvements have been made in the sensitivity of test procedures and apparatus so that smaller samples have become sufficient for each test, the number of different test procedures and the importance of having the capability for redundant or confirming testing still necessitates having a suitable sample size.
Samples can be obtained in sufficient size by using larger biopsy needles. However, larger needles and sample collecting can be uncomfortable or painful for the patient because they require larger incisions or holes. Larger holes carry an increased risk of iatrogenic complications. If the invaded pathway to the area of the body of interest is reduced in diameter, discomfort and pain are minimized, healing is quicker, scars are less likely to form and the procedures can be done more simply and there is a decrease in the expected mobidity and mortality.
Accordingly, there is a need for a biopsy needle that obtains and secures a sufficiently large sample of tissue with a minimal incision.